The present invention relates to a pen which lies flat, when it is not being used for writing, and can be used as a bookmark when unfolded. When the pen is to be used for writing, it folds into a triangular prism, so that it can be easily grasped by the hand.
Pens of the state of the art have a barrel which have generally either a circular, hexagonal, or triangular cross-sectional shape. While pens with barrels of these shapes are easy to hold when they are being used for writing, these barrels also have certain disadvantages, due to their thickness and shape.
When a person, such as a student, is using a pen to make notes of the contents of a book, it is not uncommon for the person to use the pen as a bookmark. But due to the thickness of the barrel, damage to the book can occur, if the book is closed while the pen is between the pages.
Furthermore, while it is possible to put writing, such as advertising, on the exterior of the barrels of pens of the state of the art, their shapes do not make it easy to do so. In addition due to their shapes not too much writing can be printed on the barrel nor is it easy to read it.